B.K.S. Iyengar is credited with introducing the practice of yoga, one of the six schools of the ancient Vedic/Hindu philosophy from India, to the Western world. The series of physical postures, or asanas, are deemed to be beneficial to the mind, body, and spirit. Iyengar founded his own institute in India, and his devotees went on to open their own schools around the world. Iyengar was named to Time magazine's "Time 100" list of heroes and icons for 2004. "Iyengar teaches practitioners to lavish attention on the body," wrote actor Michael Richards in that issue's tribute. "The goal is to tie the mind to the breath and the body, not to an idea."

Iyengar was born in 1918 into a poor family in Karnataka, India, and given the name Bellur Krishnamachar Sundararaja. He was the thirteenth child in his family, and arrived during the global influenza epidemic. His mother had come down with it, and as as a result Iyengar was born weak and frail, and suffered from health problems during his youth. He emerged from bouts of malaria, typhoid, influenza, tuberculosis-all potentially deadly illnesses at the time-even frailer, and doctors claimed he would not live to see his twenty-first birthday. When he was nine years old, his schoolteacher father died, and he went to live with a brother in Bangalore.

As a teenager, Iyengar was stiff as well as frail because he had spent so much time ill in bed. His schoolwork suffered, and he failed his examination in English, which meant he could not go on to college. One of his sisters was married to a famous yoga teacher in India, T. Krishnamacharya, and Iyengar realized that those he knew who practiced yoga seemed much healthier than others who did not. While living with his sister and her husband in Mysore, he asked his brother-in-law to teach him, and Krishnamacharya did so only with reluctance at first, predicting that Iyengar would never be able to meet the physical demands. But Iyengar impressed Krishnamacharya when a favorite student in the household disappeared just before an important demonstration was to take place, and Iyengar quickly learned the postures and executed them perfectly.

Iyengar began to travel with his brother-in-law, giving demonstrations across Karnatak Province. When a group of women requested their own teacher, Krishnamacharya sent Iyengar, though he was the youngest among his students. In time, his health vastly improved, Iyengar would walk from village to village demonstrating yoga. Living like a true ascetic, he ate only rice and water, or sometimes a slice of bread. His family began to worry about him, and a marriage was arranged in 1943, as was the custom. But his new wife, Ramamani, agreed to help him pursue his goal, and he began teaching her yoga.

Due to his intense yoga practice of ten hours a day, Iyengar gained increasing renown in India as a yogi, or yoga master, and famed violinist Yehudi Menuhin heard about his innovative style. In Bombay in 1952, Iyengar received word that Menuhin wanted to meet him, and he traveled seven hours by train to a meeting that was scheduled to last just five minutes. Instead it stretched more than three hours, and eventually led to a series of classes for Menuhin. The health-conscious musician asserted to the media that yoga had improved his concentration and playing. In appreciation of what yoga had done for him, Menuhin presented Iyengar with an Omega wristwatch bearing the inscription "To my best violin teacher-B.K.S. Iyengar." Menuhin also engineered introductions to other musicians in Switzerland and England as well as to Belgium's Queen Mother who became his avid student. In 1956, Iyengar traveled to the United States for the first time, and even demonstrated his asanas for Soviet leader Nikita Khrushchev. He wrote a book, Light on Yoga, which was published in 1966 and featured detailed instructions on more than 200 asanas. It would become a standard reference text for the growing number of yoga teachers in the West.

Iyengar was finally able to establish his own institute in Pune, India, in the early 1970s. He named it the Ramamani Iyengar Memorial Institute in honor of his wife, who died in 1973. By the time its doors opened, the Iyengar style of yoga-a strenuous physical workout based on the principles of Patanjali yoga-had caught on with others around the world. Groups began forming in the United States and Europe, and a number of schools and institutes were founded by devotees who had been trained in Pune. Iyengar's yoga uses props, such as weights, pulleys, stools, and ropes, to help students perfect the postures. Stressing the pranayama, or breathing techniques, Iyengar encourages his students to overcome obstacles of the spirit. "The mind is the maker and the mind is the destroyer," he wrote in Light on Yoga, according to Investor's Business Daily journalist Sonja Carberry. "On one side the mind is making you and on the other side it is destroying you. You must tell the destructive side of the mind to keep quiet-then you will learn."

Iyengar retired from teaching full-time in 1984, when he was 66 years old, but continued the medical classes and the occasional regular class some two decades later. He was still demonstrating his famous headstand, which he could maintain for thirty minutes, well into his eighties. Two of his six children-daughter Geeta and son Prashant-run the school in Pune. His book Light on Yoga remained in print nearly 40 years after it was first published, in 18 languages. A new 1995 edition included a foreword by Menuhin. "It's hard to imagine how our yoga would look without Iyengar's contributions," noted Yoga Journal writer Fernando Pagés Ruiz, "especially his precisely detailed, systematic articulation of each asana, his research into therapeutic applications, and his multi-tiered, rigorous training system which has produced so many influential teachers."
Yoga vastly increased in popularity in the 1990s, with new schools and styles coming into vogue in the West. Iyengar was dismissive of the trend, especially what he viewed as the yoga-for-profit mindset of some schools. "I think many of my students have followed the advice I gave years ago," he told New York Times writer Amy Waldman, "to give more than you take. The commercialism may wash off sometime later." He also recalled in the same interview the prediction of his doctors when he was younger that he would be lucky to reach adulthood. Yoga, he told the newspaper, "has given me a bonus of 65 years."